An international team of researchers has identified key networks within the brain they say interact to increase the risk that an individual will think about - or attempt - suicide.
In an article published today in Molecular Psychiatry, the researchers say their review of existing literature highlights how little research has been done into one of the world's major killers, particularly among the most vulnerable groups.
Around 800,000 worldwide people die by suicide every year, the equivalent of one every 40 seconds. Suicide is the second leading cause of death globally among 15-29 year olds. As many as one in three adolescents think about ending their lives and one in three of these will attempt suicide.
The international HOPES team (Help Overcome and Prevent the Emergence of Suicide), led by Associate Professor Lianne Schmaal from Orygen alongside Dr Anne-Laura van Harmelen from the University of Cambridge and Professor Hilary Blumberg from the Yale School of Medicine, carried out a review of two decades' worth of scientific literature relating to brain imaging studies of suicidal thoughts and behaviour. In total, they looked at 131 studies, which covered more than 12,000 people, looking at alterations in brain structure and function that might increase an individual's suicide risk.
Associate Professor Schmaal said the biggest predictor of death by suicide is a previous suicide attempt.
It's therefore essential that we intervene as early as possible to reduce an individual's risk. For many individuals, this will be during adolescence. If we can work out a way to identify those young people at greatest risk, then we will have a chance to step in and help them at this important stage in their lives."
Lianne Schmaal, Associate Professor
Combining the results from all of the brain imaging studies available, the researchers looked for evidence of structural, functional, and molecular alterations in the brain that could increase risk of suicide. They identified two brain networks - and the connections between them - that appear to play an important role.
The first of these networks involves areas towards the front of the brain known as the medial and lateral ventral prefrontal cortex and their connections to other brain regions involved in emotion. Alterations in this network may lead to excessive negative thoughts and difficulties regulating emotions, stimulating thoughts of suicide.
The second network involves regions known as the dorsal prefrontal cortex and inferior frontal gyrus system. Alterations in this network may influence suicide attempts, in part, due to its role in decision making, generating alternative solutions to problems, and controlling behavior.
The researchers suggest that if both networks are altered in terms of their structure, function or biochemistry, this might lead to situations where an individual thinks negatively about the future and is unable to control their thoughts, which might lead to situations where an individual is at higher risk for suicide.
Associate Professor Schmaal said the two brain networks could be important targets for the generation of more effective suicide prevention strategies.
Schmaal, L., et al. (2019) Imaging suicidal thoughts and behaviors: a comprehensive review of 2 decades of neuroimaging studies. International Molecular Psychiatry. doi.org/10.1038/s41380-019-0587-x.